This invention relates to swim fins and more particularly to swim fins which may be used effectively for swimming and for walking.
Swim fins are devices which are worn on a swimmer's feet to provide an increased surface for acting on the water and to flexibly flutter in the water while the swimmer kicks. The fins thus permit the swimmer to generate greater propulsive force and efficiency while swimming. However, the fins are bulky and cumbersome when worn while walking on land because of the generally uninterrupted length of the fin from the mounting portion of the foot of the wearer to the free or forward end of the web or blade of the fin. Conventional fins are thus impracticable for use while walking and must be installed at the water's edge and removed when exiting from the water.
Various proposals have been made in the prior art to provide swimming fins which may be less cumbersome when walking than conventional fins. Many of the proposals are complex or provide ineffective means for locking the web of the fin in either or both the swimming or walking mode. Exemplary of this prior art are Wozencraft U.S. Pat. No. 2,903,718 which merely unlatches a portion of the fin and permits it to swing so as to drag behind the swimmer's foot; Markowitz U.S. Pat. No. 3,268,927 which requires a large awkward boot for carrying a strut on which a lever is pivoted; Tackett et al U.S. Pat. No. 4,752,259 which hinges the web so that it pivots onto or under the foot where it is held by magnets; Klein U.S. Pat. No. 4,981,454 which pivotably hinges the web but does not latch it in the walking position; Italian Patent No. 533,240 which hinges and pivots the web from a latched swimming position but requires a brace about the leg to hold it in the walking position; French application No. 2,565,498 which uses a lever to pivot the web; and Russian Inventor's Certificate No. 1,189,460A which hinges the web and pivots it against the action of an over-center spring.
In none of the known prior art proposals is there a positive locking of the web portion of the fin to the foot mounted portion in both the swimming and the walking mode while permitting the blade to flexibly flutter during the swimming mode. Accordingly, although a substantial number of proposals have been made to solve the aforesaid problem, these proposals have not provided feasible solutions and appear not to have been adopted commercially.